Effect of substrate doping on threshold voltages of buried channel pMOSFET based on strained-SiGe technology

Abstract

The effect of substrate doping on the threshold voltages of buried channel pMOSFET based on strained-SiGe technology was studied. By physically deriving the models of the threshold voltages, it is found that the layer which inversely occurs first is substrate doping dependent, giving explanation for the variation of plateau observed in the C-V characteristics of this device, as the doping concentration increases. The threshold voltages obtained from the proposed model are −1.2805 V for buried channel and −2.9358 V for surface channel at a lightly doping case, and −3.41 V for surface channel at a heavily doping case, which agrees well with the experimental results. Also, the variations of the threshold voltages with several device parameters are discussed, which provides valuable reference to the designers of strained-SiGe devices.

Keywords

buried pMOSFET / strained SiGe / plateau / threshold voltage / substrate doping / Ge fraction

References

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